Bulletin of the American Physical Society
74th Annual Meeting of the APS Division of Fluid Dynamics
Volume 66, Number 17
Sunday–Tuesday, November 21–23, 2021; Phoenix Convention Center, Phoenix, Arizona
Session P05: Porous Media Flows: Convection and Heat Transfer III |
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Chair: Yaofa Li, Montana State University Room: North 121 C |
Monday, November 22, 2021 4:05PM - 4:18PM |
P05.00001: Drying Dynamics of Hydrogels Jean-Francois Louf, Christopher A Browne, Tapomoy Bhattacharjee, Sankaran Sundaresan, Sujit S Datta The swelling of deformable porous media, like hydrogels, has been widely investigated for several decades. In contrast, their drying dynamics have received far less attention despite their pivotal importance for coatings, geomechanical processes, and even the functioning of plants. In this study, we combine 3D visualization using confocal microscopy with macroscopic measurements of drying hydrogel layers to elucidate the underlying physics. Our direct measurements of the internal hydrogel strain reveal that it is not homogeneous, in stark contrast to common assumptions. Instead, the rapid formation of a dry crust produces a spatially-varying permeability (k) and Young’s modulus (E). Leveraging our measurements, we propose a modified drying model that quantitatively captures the measured drying rate over a broad range of temperatures and relative humidity. |
Monday, November 22, 2021 4:18PM - 4:31PM |
P05.00002: The wicking of volatile drops on thin porous substrates Garam Lee, Samira Shiri, C. Frederik Brasz, James C Bird A liquid droplet deposited onto a thin porous substrate can penetrate into the media and then spontaneously spread radially outward. The spreading of a non-volatile drop follows power-law dynamics set by a balance of capillarity and viscosity. However, if the drop is volatile, the precise effect of evaporation on the wicking dynamics is not well understood. Here we measure and model how evaporation limits the extent that the droplet spreads, reversing the direction of the liquid front so that the droplet shrinks in size after reaching a maximum diameter. Through a series of systematic experiments, we investigate the evaporation rate and the wicking dynamics, both of which can be predicted with relatively simple models. These results provide insight into the size of stains deposited by droplets on porous substrates such as paper or fabric. |
Monday, November 22, 2021 4:31PM - 4:44PM |
P05.00003: Using high-speed micro-PIV to investigate pore-scale interactions of liquid CO$_2$ and water in 2D porous micromodels with varying wettabilities Yaofa Li, Gianluca Blois, Farzan Kazemifar, Razin Sazzad Molla, Kenneth T Christensen Multiphase flow of supercritical CO$_2$ and water in porous media is relevant to geologic carbon sequestration and enhanced oil recovery, among many other applications in the energy and environmental sectors. Resolving pore-scale transient flow dynamics is crucial to understanding the underlying physics and informing large-scale predictive models. To that end, an experimental investigation of the pore-scale flow dynamics of liquid CO$_2$ and water in two-dimensional (2D) circular porous micromodels with different surface characteristics is conducted employing high-speed microscopic particle image velocimetry (micro-PIV). The design of the micromodel minimized side boundary effects due to the limited size of the domain. The high-speed micro-PIV technique resolved the spatial and temporal dynamics of multiphase flow of CO$_2$ and water under reservoir-relevant conditions, for both drainage and imbibition scenarios. These novel measurements enable direct observations of the meniscus displacement, revealing a significant alteration of the pore filling mechanisms during drainage and imbibition. And pore-scale velocity fields were statistically analyzed to provide a quantitative measure of the role of capillary effects in these pore flows. |
Monday, November 22, 2021 4:44PM - 4:57PM |
P05.00004: An Experimental Study of Capillary Pressure Hysteresis in Two-phase Flow in 2D Porous Micromodels Razin Sazzad Molla, Yaofa Li Two-phase immiscible flow in porous media occurs in many environmental and industrial systems. Traditional models often describe these flows based on empirical constitutive relations (e.g., capillary pressure vs. saturation) which exhibit hysteresis. It has been the goal for many recent studies to develop a nonhysteretic relation of capillary pressure to link pore to macro-scale through thermodynamically constrained averaging theory (TCAT) and geometric measures. However, experiments are still needed to validate and further develop the theories. To that end, we present a pore-scale measurement of capillary pressure, saturation, interfacial area, curvature, and Euler characteristic employing 2D microfluidic devices called micromodels and high-speed fluorescent microscopy. The uniqueness of the capillary pressure-saturation relation under different flow histories is investigated. We further discuss the geometric theorems applicable to two-phase constitutive relation and how the inclusion of new variables in the model reduces hysteresis under quasi-static and transient conditions. These results will provide new insight into the hysteretic behavior of capillary pressure as well as validations of new functional forms. |
Monday, November 22, 2021 4:57PM - 5:10PM |
P05.00005: Dynamic permeability reduction and scaling of flow in porous media Shima Parsa, Adam Hsu, Andres O Gonzalez Precipitation of minerals, adsorption of nanoparticles and trapping of immiscible fluids in porous media result in changes in the available flow paths and modify the permeability of the medium. We use confocal microscopy and bulk transport measurements to probe the local flow and permeability of the medium in 3D porous micromodels. Our experimental measurements show that depending on the time allowed for changes in the structure and response from the flow, the structure of the medium self-regulates. Nevertheless, the probability distribution of fluid velocities retain the same shape. We find that at a constant volumetric flow rate, the self-regulated media have an intrinsic length-scale that can be estimated from the bulk permeability of the medium. |
Monday, November 22, 2021 5:10PM - 5:23PM Not Participating |
P05.00006: Intermittency effects in single- and multi-phase flows in porous media Zoƫ Penko, Yaofa Li, Diogo Bolster, Kenneth T Christensen Multi-phase flow and transport in porous media is prevalent in a wide range of challenging fluid mechanics problems in sustainability, energy, and the environment. Accurate prediction and understanding of the underlying flow physics is vital in addressing these problems, particularly the small- or pore-scale study of the flow's spatial and temporal evolution, which can impact flow behavior at system scales in a nontrivial manner. Intermittency is a phenomenon observable at the pore scale in both numerical and experimental studies of single-phase flow, but the case of multi-phase flow more commonly found in natural systems has yet to receive much attention due to the challenges faced in both simulations and experiments. We present results from a computational and experimental study of intermittent behavior over a range of flow regimes in single- and multi-phase flows in 2D homogeneous and heterogeneous micromodels. Lagrangian flow statistics are obtained by Lattice Boltzmann simulations and particle tracking velocimetry (PTV) measurements to draw comparisons between computational and experimental results. The results make note of the applicability of different modeling frameworks such as the correlated-continuous time random walk. |
Monday, November 22, 2021 5:23PM - 5:36PM |
P05.00007: Steady Moving Cracks in Drying Colloidal Films: Three Limits ATIYA BADAR, Mahesh S Tirumkudulu The drying of dispersions containing colloidal particles is encountered in many applications such as in processing of ceramic materials, film formation in paints and coatings, and synthesis of photonic bandgap materials. In many cases, shrinkage stresses generated during drying fracture the film. While much of the previous work has focused on cracking in static cracks, there are very few studies on the dynamics of cracks in colloidal coatings. The problem is complex as one needs to account for the mechanics of the particle network, flow of the interstitial fluid and the dynamics of crack motion. Here, we adopt the constitutive relation proposed by Russel and co-workers for a saturated packing of colloidal spheres to derive analytical solution for the stress, displacement, and pressure fields near the crack tip for a steady moving crack. To simplify the problem, first we consider the two extreme cases, namely, the high speed limit (undrained case) where the crack motion is much faster than Darcy flow rate and the opposite extreme of very slow crack propagation i.e low speed limit (drained case). Next, we take the general case where crack-tip motion is comparable to that for the interstitial flow time. The results incorporate micro-structural details of the system including particle volume fraction and nature of packing, and particle's mechanical properties such as modulus and Poisson's ratio. While predicted results are in line with similar results obtained for brittle materials, the predicted crack speeds are at least an order of magnitude higher than those observed in experiments. This difference is purely depends on difference in inertial effects of particle and fluid phases near the crack tip. |
Monday, November 22, 2021 5:36PM - 5:49PM Not Participating |
P05.00008: Manipulating Viscous Fingering of Complex Fluids Alban L Pouplard, Peichun Amy Tsai We demonstrate the feasibility of controlling the viscous fingering instability of complex (yield-stress) fluids when a less-viscous fluid pushes another immersible one in a narrow cell. We experimentally show that a radially tapered cell, implying a permeability gradient, can be used to inhibit the viscous fingering instability of a complex yield-stress fluid. We observe a stable flat or wavy finger-like interface using two different yield-stress fluids experimentally depending on the gap gradient, the injection flow rate, and local rheological parameters. Furthermore, we develop a theoretical linear-stability analysis generalized for common complex fluids possessing a power-law varying viscosity and yield stress. A critical criterion differentiating a stable and unstable viscous fingering interface is established and is consistent with the experimental results of fluid-fluid displacement with the complex fluids. |
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